Alloy



UNITED STATES P am OFFICE.

FREDERICK MARK BECKET, OF NIAGARA FALLS, NEW YORK, ASSIGNOB TO ELECTED METALLURGICAL COMPANY, OF NIAGARA FALLS, NEW YORK, A CORPORATION OF WEST VIRGINIA.

Patented Mari 9, I920.

ALLOY.

1,333,151,, Specification of Letters Patent.

No Drawing.

To all whom it may concern:

Be it known that I, FREDERICK M. Bncxn'r, a citizen of the United States, residing at Niagara Falls, in the county of Niagara and State of New York, have inventedv certain new and useful Improvements in Alloys, or: which the following is a specification This invention relates to a novel alloy containing as essential components chromium, man ese and iron proportioned to impart to alloy certain distinctive properties, among ich are a high degree of resistance to 0.: :tion in combination with a relatively low magnetic permeability. This combination of properties in a machinable andv forgeable alloy renders the product useful for a wide variety otpurposes, including such special applications as electrode heads for electric furnaces, and other furnace parts which are so located with relation to the electric circuit that .a material of high magnetic permeability would lower the power factor of thefurnace,

The'desirable and distinctive properties of the alloy have been found to exist throughout a rather wide range of proportions of the principal components, but in general my invention contemplates an alloy comprising I Chromium IO-4C5 per cent. Manganese 2P2. Carbon 0- 3 r Silicon 0- 3 the balance being principally iron, and the chromium predominating over the manganese.

While serviceable alloys may be made throughout range specified above, I prefer for most purposes an alloy wherein the chromium content is between 15 and 35 per cent, the percentage manganesegbeing always less than tiat of the chromium and being comprised between the limits of 5 and 15 per cent. In this preferred embodiment of the invention carbon is present to the extent of 0.1 to 2.0 per cent. and silicon within the same limits.

The specific composition of the alloy will of course be varied according to the particular characte t'istics and properties desired, and in accordance with its intended use. Throughout the range specified the alloy possesses the following properties:

Application filed September 26, 1919. Serial No. 326,504.

(1) A high degree of resistance to oxidation even at very high temperatures. 'In general the alloys may be heated in air to 1000-1100 C. or higher without destructive efiects. For example, samples exposed to air at a temperature of 1050 C. for 120 hours have shown oxidation losses of the order of 1.03.0%, after mechanically remoV-- Under identical conditions general the permeability tends to. decrease with increasing percentages of manganese or of carbon, or of manganese and carbon. Permeability not exceeding '25 per cent. of that of cast iron is readily attained.

(3) A high tensile and transverse strength relative to cast iron. As a rule the tensile strength of the cast alloy is upward of 30,000 lbs. per square inch, and usually of the order or a0,000%5,000 lbs. or higher. The transverse strength is in general from 14- to 2 times that of cast iron.

(4) The alloys are highly responsive to heat treatment as compared with cast iron. For example by heating the cast alloy to l000-1100 C. for several hours (depending upon the size of the piece) and then cooling in the furnace, its tensilestrength may be increased 5080 per cent. The forged al loys are likewise responsive to similar heat treatment, and in this way alloy articles having a tensile strength in excess of 100,000 lbs. per square inch have been made.-

(5) The alloys are machinable and forgeable, these qualities being somewhat "more pronounced in the alloys having the lower content of manganese and of carbon. With very high chromium content the alloys are less readily forgeable, but are machinable.

' The alloys may be prepared in various ways. For example high grade ferro-manganese or manganese metal may be added to ferrochromium in the required proportlons, with or without the addition of hog in the form of steel scrap or otherwise, the charge being melted and mixed in electrically heated crucibles. They may likewise be 'prepared by direct smelting in an electric furnace of a charge containing ores of chromium and of manganese, with or without scrap steel or other form of iron. In such operations silicon or ferrosilicon is preferably employed as the reducing agent.

Relatively small proportions of other elements, including tungsten, zirconium, vanadium, titanium, nickel, aluminum, 'etc.,

. may be introduced into the alloy without departing from my invention.

Analyses of representative alloys in accordance with my lnvention have shown:

Chromium 30. 21 24. G0 23. O8 Mani'anese. 4. 10. 24 19.00 Carbon 1.23 1.08 1.20 Sllicon..... 0.18 0.95 0.49 Iron 63. 63 62. 37 56. 10

Of the above typical examples, the magnetic permeability of (1) was of the order of 1} to that-of cast iron. That of (2) and (3) was about 2-'5% of that of cast iron.

ing:

Chromium; 10-45% Manganese 3-Z5% Carbon 0- 3% Silicon 0- 3% 40 the balance being principally iron.

.2. A machinable alloy characterized by its resistance to oxidation at high temperatures, its low magnetic permeability relative to steel and cast iron, and by its respon- 'sivcness to heat treatment, said alloy comprising:

Chromium 15-85% Manganese- 5-15% Carbon 0.1- 2% Silicon 0.1- 2% the balance being principally iron.

In testimony whereof I aflix. my signature.

FREDERICK MARK BECKET. 

